This invention generally pertains to methods for adding process integration to the manufacture of fiber-optic apparatuses implemented with side-polished fiber optics. This invention also pertains to integrated apparatuses made from these methods of manufacture.
There is no prior art method or apparatus published, or on the market, for fully utilizing the advantages of integrated processes with silicon to manufacture side-polished fiber-optic apparatuses and systems, other than the photomasking of multiple features such as grooves, or the deposition of coatings. What is known in the prior art deals with individually placing fibers in grooves, one-at-a-time. Once placed they may all be polished in one step. This prior art is limited to the manufacture of side-polished fibers to implement two-port photonic functions. This known art is taught in the U.S. Pat. No. 5,781,675 “Method for preparing fiber-optic polarizer” and U.S. Pat. No. 5,809,188 “Tunable optical filter or reflector”, both by Tseng. In those patents, Tseng teaches the use of a set of parallel and variable-depth V-grooves etched in a common silicon crystal substrate to simultaneously achieve both a) precise control of remaining side-wall thickness left on each fiber held within each of the V-grooves, b) arcuate paths for the fibers which enable the side-polished regions to be of a controlled length, and c) simultaneous deposition of one or more films on the set of side-polished regions. Not taught in the above patents are multi-function apparatuses or methods for manufacturing multiple apparatuses on a common fiber without fuse splicing or physical connectors. Also not disclosed are a) methods or apparatuses for fabricating multiple units simultaneously, other than the substrates themselves or 2-port polarizers or filters; b) methods or apparatuses wherein some multiples of individual apparatuses are formed with at least one fiber in common; or c) any methods or apparatuses for fiber-to-fiber alignment when coupling side-polished areas to one another between fibers in respectively different substrates.
Earlier art teaches side-polished fiber optics made by retaining the fiber within a groove cut into the surface of a non-crystalline material such as glass or quartz. This art can be found in such U.S. patents as U.S. Pat. No. 4,493,528 “Fiber-optic directional coupler”, U.S. Pat. No. 4,536,058 “Method of manufacturing a fiber-optic directional coupler”, U.S. Pat. No. 4,556,279 “Passive fiber-optic multiplexer”, U.S. Pat. No. 4,564,262 “Fiber-optic directional coupler”, U.S. Pat. No. 4,601,541 “Fiber-optic directional coupler”, U.S. Pat. No. 6,011,881 “Fiber-optic tunable filter”, all by Shaw. This art also teaches the requirement of one side-polished fiber along side of a second side-polished fiber, but fails to disclose any means of mechanical self-alignment.
Earlier art also includes apparatuses and methods of aligning optical components using constant-depth V-grooves in the surfaces of silicon substrates. Three examples include U.S. Pat. No. 5,633,968 “Face-lock interconnection means for optical fibers and other optical components and manufacturing methods of the same” by Sheem, U.S. Pat. No. 4,475,790 “Fiber-optic coupler” by Little, and U.S. Pat. No. 4,802,727 “Positioning optical components and waveguides” by Stanley. Another U.S. patent, U.S. Pat. No. 4,688,882 “Optical contact evanescent wave fiber-optic coupler” by Failes, not only references some of the earliest work of constructing substrate-supported, side-polished, fiber-optic apparatuses, but also describes some of the limitations involved. This patent by Failes teaches a method of achieving a fused coupling between side-coupled fibers that doesn't require the index-matching coupling fluid of previous works. Failes did not offer any approaches to precisely and rigidly support the fibers through intimate contact with respective hard substrates.
Another relevant prior art is that of U.S. Pat. No. 5,187,760 “Wavelength selective coupler for high power optical communications” by Huber. This patent references little of the above prior art, and is evidently what is called a “non-enabling” patent because it does not provide the reader with information on how to practically implement the structures described and claimed. It describes the use of gratings with which to couple light within a wavelength band between a first fiber and a second fiber. In fact it also describes doing this at more than a single location along the length of the second fiber, wherein the multiple first fibers have respective gratings with different wavelength bands. What is needed is a practicable way in which to implement such structures and apparatuses successfully.
Additional prior art on positioning of fiber optics on substrates is found in the technology of Microelectronic Mechanical Systems (MEMS). One reference to such technology is that of “MEMS Packaging for Micro Mirror Switches”, by L. S. Huang, S. S. Lee, E. Motamedi, M. C. Wu, and C. J. Kim, Proc. 48th Electronic Components & Technology Conference, Seattle, Wash., May 1998, pp. 592–597.
None of the above art, with the exception of a co-pending application entitled “Structures and Methods for Aligning Fibers”, by Tullis, now issued as U.S. Pat. No. 6,516,131, teaches methods or apparatuses for facilitating the placement of an array of fibers into an array of grooves of width comparable to the diameter of the fiber.
Practicable methods and apparatuses are needed to achieve simultaneous assembly of fibers into precision grooves in supporting substrates.
The current invention goes beyond one-at-a-time fabrication and introduces process integration methods by which to greatly reduce the cost of manufacturing side-polished fiber-optic apparatuses. Furthermore, the current invention makes possible the integration of compact arrays of side-polished apparatuses that can be used to implement high levels of function integration. And not all of the multiple apparatuses manufactured on a common substrate need be of the same type.